Cinnamon, formerly known as C. loureirii and also known as cassia, Chinese cinnamon, etc., first appears in “Tang materia medica” and is first recorded in “Shennong's classic of materia medica”; it is the dry bark of Cinnamomum cassia Presl. mainly produced in the provinces of Guangdong, Guangxi, Yunnan and so on; the bark with a fragrance may be used as a flavoring and is an edible and medicinal plant material disclosed by China's Ministry of Health.
Cinnamon is pungent, sweet and hot in nature, and goes to the channels of kidney, spleen, heart and liver; it has the effects of supplementing heat, reinforcing yang, dissipating cold, relieving pain, warming channels and unblocking vessels, and is widely used in clinical practice for the symptoms of deficiency in kidney yang, decline of fire in life gate, decline of yang in spleen and kidney, and cold and pain in gastral cavity. The main effective components of cinnamon are volatile oil, terpenoids, flavanols and the like, wherein the content of volatile oil is 1.2%˜2%. Cinnamon oil is yellow or brownish yellow clear liquid, and is generally obtained by steam distillation; it has the specific fragrance of cinnamon, a sweet taste, a relative density of 1.055˜1.070, and a refractive index of 1.602˜1.614. Cinnamon oil has a main chemical component of cinnamaldehyde, with additionally methyl eugenol, cinnamic alcohol, cinnamyl acetate, coumarin, vanillin, eugenol and the like. Modern research has found that cinnamon oil has sedative, analgesic, antipyretic, anticonvulsant, gastrointestinal peristalsis-enhancing, choleretic and antitumor effects; it is a main raw material in pharmaceutical, food and chemical industries, and is more commonly used in food such as beverage, confectionary, canned food and the like in food industry. Consequently, cinnamon oil has enormous application prospects in the development of health food and novel medicines, and has great value in research and utilization.
Currently, the methods for extracting cinnamon oil mainly include steam distillation, solvent extraction, supercritical CO2 extraction and the like. Steam distillation is immersional wetting and then distilling the coarse powders or flakes of cinnamon by direct heating or introducing steam, condensing and then collecting the volatile components brought out with steam distillation, and obtaining essential oil after oil-water separation. Steam distillation as a conventional method for extracting essential oil has the advantages of simple equipments, easy operation, no organic solvent retention and the like. However, this method also has the disadvantages of high extraction temperature, large energy consumption, long extraction time and a low yield of essential oil. In addition, long heating time easily causes loss of effective components, and meanwhile, the raw material will be charred when overheating, producing an adverse effect on the fragrance of the essential oil. Solvent extraction typically uses organic solvents such as petroleum ether, n-hexane, ethanol and the like for extraction; the oil obtained by extraction mostly contains some non-volatile components, and there tend to be much phenomenon of solvent retention when separating these solvents from the essential oil, depriving the product of naturality. Supercritical CO2 has special properties determining its unique superiority with respect to the extraction of oil and of nonpolar substances such as natural ingredients and the like, namely high speed and yield, and thus is widely applied to the extraction of the components of flavorings and medicinal herbs. However, there are a strict requirement for and a great investment in the equipments due to the need for a high pressure environment; the small volume of extraction tanks due to the high pressure state for extraction and the limited production capacity make it unable to form large-scale industrial production, imposing a high cost on the product.
Therefore, it is always an urgent problem to be solved by the manufacturers in this industry to find a method for extracting cinnamon oil with low energy consumption, a short time, substantially no solvent retention and meanwhile a high yield, as well as the easiness to realize industrialization.